Novell BUSINESS CONTINUITY CLUSTERING 1.1 SP2 - ADMINISTRATION, Administration Manual

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Overview 17
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A cluster of clusters provides the ability to fail over selected cluster resources or all cluster resources
from one cluster to another cluster. For example, the cluster resources in one cluster can fail over to
separate clusters by using a multiple-site fan-out failover approach. A given service can be provided
by multiple clusters. Resource configurations are replicated to each peer cluster and synchronized
manually. Failover between clusters requires manual management of the storage systems and the
cluster.
Nodes in each cluster access only the storage systems co-located in the same data center. Typically,
data is replicated by using storage-based mirroring. Each cluster has its own SBD partition. The
SBD partition is not mirrored across the sites, which minimizes the chance for a split-brain problem
occurring when using host-based mirroring. For information about using mirroring solutions for data
replication, see
Section 1.2.2, “Host-Based versus Storage-Based Data Mirroring,” on page 14 .
In the cluster-of-clusters architecture shown in Figure 1-2 , the data is synchronized by the SAN
hardware between two data centers that are geographically separated. If a disaster occurs in one data
center, the cluster in the other data center takes over.
Figure 1-2
Cluster of Clusters
Cluster Site 2 Cluster Site 1
Fibre Channel
Switch
Fibre Channel
Disk Arrays
Building A Building B
Ethernet Switch
Fibre Channel
Switch
Fibre Channel
Disk Arrays
Disk blocks
Ethernet Switch
WAN
eDirectory
IDM
Two independent clusters at
geographically separate sites
SAN
Server
2B
Server
3B
Server
1B
Server
4B
Server
2A
Server
3A
Server
1A
Server
4A